Improvement in printing-inks



UNIT D STATES PATENT OFFICE.

GEORGE MATTHEWS, OF MONTREAL, CANADA EAST.

IMPROVEMENT lN PRlNTlNG-lNKS.

Specification forming part of Letters Patent No. 17,688, dated June 30, 1857.

To all whom it may concern:

Be it known that I, GEORGE MATTHEWS, of Montreal, in the Province of Canada East, haveinvcnted a new and useful improvement in the composition of ink suitable for printing and coloring or shading bank-notes and other instruments and documents by the copperplate, lithographic, typographic, xylographic, or other processes of printing; and 1 do hereby declare that the following is a full, true, and exact description ofmy said improvement and of the mode of preparing and using the same.

The nature of my invention consists in using for the basis and coloring ingredient of the ink the article known and usually designated as the calcined green oxide of chromium, (known to chemists as the anhydrous sesquioxide of chromium,) which I mix with burned or boiled linseed-oil, sometimes called printers varnish, in the manner usual in preparing ink for printing bank-notes or other instruments by either of the above processes of printing. When printed upon bank-note or other paper usually used in printing, its color or tint is unalterable by the action of light, air, or sulphurous vapors, and it is insoluble in nitric, muriatic, or other acids, orin caustic alkalies, and only soluble in boiling oil of vitriol.

Unlike every colored ink heretofore used or known, the ink prepared with this ingredient resists every known agent which can be employed to dissolve it from the paper or eft'ace it therefrom, or to change its color, and it can only be efiaeed by destroying the face and surface of the note or instrument in the printing of which it is used. It thus presents asecurity heretofore unattained against alteration and counterfeiting by photography or any other known process.

The calcined green oxide of chromium usually is obtained in the form of powder or small particles, and it is made or prepared from bichromate of potash by mixing about one and one-half part of flour of' sulphur with four parts of the bichromate in fine powder, heating these two to redness in a crucible or furnace, and keeping the mass in this state for about half an hour. When the massis 'cool it is to be thrown into water, or washed in plenty of water until all the salts are removed. Then dry it thoroughly in the air. Then let the mass be broken fine and heated to redness a second time for the purpose of expelling the sulphur and any water or moisture that may remain. This process produces the chromium in a state of powder or small particles. For preparing it and making it into the ink for printing by the above-mentioned processes, this powder is ground or triturated upon the ordinary inkstone with a suflieient quantity of burned or boiled linseed-oil, or printers varnish, as it is called, as is customary in preparingink for such use, and by this process the composition or ink is made. It is mixed with a proper quantity of boiled or burned linseed-oil to produce the consistency required for printing-ink.

The degree of consistency required varies somewhat, according to the purpose for which the ink is to be used; but any experienced workman or printer can easily judge of the consistency required of the ink, according as it is to be used for bank-note engraving, lithographic, typographic, or any other kinds of printing for which ink is required. It is not necessary to use any other ingredients to make the ink than the chromium thus prepared and the burned or boiled linseed-oil.

The ink is put upon the steel, copper, or other plates or types used for printing in the manner usual with printers in printing by those processes, respectively, and the color produced upon the bank-note or other instrument by this ink is'a delicate but bright and clear green.

Having thus described my invention and improvement, what I claim as my invention therein, and for which I desire Letters Patent, is-- The use of the calcined green oxide of chromium for making ink for printing from en graved plates, from types, or for other kinds of printing, as described.

G. MATTHEWS.

Witnesses:

K. RAcIoor, THOS. S. WALSH, Both of the city of Montreal, Students at law. 

